The involvement of transition metal ions on iron depended lipid peroxidation

REPETTO, MARISA.; FERRAROTTI, NIDIA; BOVERIS, ALBERTO

ARCHIVES OF TOXICOLOGY.

Springer

Lugar: BERLÍN; Año: 2010 vol. 84 p. 255 - 262

0340-5761

The metals iron (Fe) and copper (Cu) are considered trace elements and the metals cobalt (Co) and nickel (Ni) are known as ultra-trace elements, considering their presence in low to very low quantity in humans. The biological activity of these transition metals is associated with the presence of unpaired electrons that favor their participation in redox reactions. They are part of important enzymes involved in vital biological processes. However, these transition metal become toxic to cells when they reach elevated tissue concentrations and produce cellular oxidative damage. Phospholipid liposomes (0.5 mg/ml, phosphatidylcholine (PC)/ phosphatidylserine (PS), 60/40), were incubated for 60 min at 37 uM of Fe2+, in the absence and in the presence of Cu2+, Co2+ and Ni2+ (0-100 uM) with and without the addition of hydrogen peroxide 5-50 uM). Iron-dependent lipid peroxidation in PC/PS liposomes was assessed by thiobarbituric acid-reactive substances (TBARS) production. Metal transition ions promoted lipid peroxidation by H2O2 decomposition and direct homolysis of endogenous hydroperoxides. The Fe2+H2O2-mediated lipid peroxidation takes place by a pseudo-second order process, and the Cu2+-mediated process by a pseudo-first order reaction. Co2+ and Ni2+ alone, do not induce lipid peroxidation. Nevertheless, when they are combined with Fe2+, Fe2+-H2O2-mediated lipid peroxidation was stimulated in the presence of Ni2+ and was inhibited in the presence of Co2+. The understanding of the effects of transition metal ions on phospholipids are relevant to the prevention of oxidative damage in biological systems.